diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc
index 55087c772..1f9944e2e 100644
--- a/frontends/ast/simplify.cc
+++ b/frontends/ast/simplify.cc
@@ -4099,16 +4099,24 @@ skip_dynamic_range_lvalue_expansion:;
 						delete arg;
 						continue;
 					}
+
 					AstNode *wire_id = new AstNode(AST_IDENTIFIER);
 					wire_id->str = wire->str;
-					AstNode *assign = child->is_input ?
-							new AstNode(AST_ASSIGN_EQ, wire_id, arg) :
-							new AstNode(AST_ASSIGN_EQ, arg, wire_id);
-					assign->children[0]->was_checked = true;
-					if (child->is_input)
+
+					if (child->is_input) {
+						AstNode *assign = new AstNode(AST_ASSIGN_EQ, wire_id->clone(), arg->clone());
+						assign->children[0]->was_checked = true;
 						new_stmts.push_back(assign);
-					else
+					}
+
+					if (child->is_output) {
+						AstNode *assign = new AstNode(AST_ASSIGN_EQ, arg->clone(), wire_id->clone());
+						assign->children[0]->was_checked = true;
 						output_assignments.push_back(assign);
+					}
+
+					delete arg;
+					delete wire_id;
 				}
 			}